When corals are mentioned, most people immediately think about clear, warm tropical seas and fish-filled reefs. In fact, the stony, shallow-water corals—the kind that build most reefs—are only one type of coral. There are also deep-sea corals that live in dark cold waters, and soft corals. In this section of the CRCP Website, you'll learn the basics about coral and coral reefs and find the answers to questions people often ask about these amazing ecosystems.

This reef in Palau demonsrates some of the biodiversity that can be found on a coral reef. Photo credit: Miles Anderson, NOAA/NCCOS/CCMA/Biogeography Branch

Coral: Plant, Animal, or Mineral?

How are corals classified? How many species are there? Find the answer to these and other questions in explanations about some basic information on coral.

Where are Corals Found?

Where in the world are corals found? Find out what are the geographic distribution and depth ranges of corals, as well as some conditions necessary for them to thrive.

Coral Anatomy and Structure

Basic coral anatomy and the differences between 'hard' and 'soft' corals are covered here.

Coral Feeding Habits

Learn how and when corals get the nutrients they need to survive.

Coral Reproduction

All corals can reproduce asexually and sexually; learn how.

From Polyp to Colony

Learn how coral reefs and other coral communities are formed, the different types of reefs, and how fast corals grow.

Turf Wars: Competing for Space to Grow

Stinging cells, external digestion, and biochemical warfare: learn about the arsenal corals can employ to claim and protect space in which to grow.

Mesophotic Coral Ecosystems

Reef-building corals are light-dependent; learn about a group of reef-building corals that live in water depths where light penetration is low.

Symbiotic Algae

Learn about the mutually beneficial symbiotic relationship reef-building corals have with a type of algae called zooxanthellae.